Patent Literature 1 describes a high-sensitivity imaging device. At noise level of an image sensor, noise generated by a circuit of an amplifier and the like is dominant. This high-sensitivity imaging device, by a process in a digital area, reduces random noise generated by a circuit of a column amplifier and the like. Patent Literature 2 describes an image sensor. An A/D converter array is provided on a CMOS image sensor column to generate a digital output. By generating a level difference between the signal level and reset level converted to digital signals, high-accuracy fixed pattern noise cancellation and random noise reduction is enabled.